70 lines
2.3 KiB
Java
70 lines
2.3 KiB
Java
//<p>给你一个正方形矩阵 <code>mat</code>，请你返回矩阵对角线元素的和。</p>
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//
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//<p>请你返回在矩阵主对角线上的元素和副对角线上且不在主对角线上元素的和。</p>
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//
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//<p> </p>
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//
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//<p><strong>示例 1：</strong></p>
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//
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//<p><img alt="" src="https://assets.leetcode.com/uploads/2020/08/14/sample_1911.png" style="height:174px; width:336px" /></p>
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//
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//<pre>
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//<strong>输入：</strong>mat = [[<strong>1</strong>,2,<strong>3</strong>],
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// [4,<strong>5</strong>,6],
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// [<strong>7</strong>,8,<strong>9</strong>]]
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//<strong>输出：</strong>25
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//<strong>解释：</strong>对角线的和为：1 + 5 + 9 + 3 + 7 = 25
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//请注意，元素 mat[1][1] = 5 只会被计算一次。
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//</pre>
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//
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//<p><strong>示例 2：</strong></p>
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//
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//<pre>
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//<strong>输入：</strong>mat = [[<strong>1</strong>,1,1,<strong>1</strong>],
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// [1,<strong>1</strong>,<strong>1</strong>,1],
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// [1,<strong>1</strong>,<strong>1</strong>,1],
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// [<strong>1</strong>,1,1,<strong>1</strong>]]
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//<strong>输出：</strong>8
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//</pre>
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//
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//<p><strong>示例 3：</strong></p>
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//
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//<pre>
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//<strong>输入：</strong>mat = [[<strong>5</strong>]]
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//<strong>输出：</strong>5
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//</pre>
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//
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//<p> </p>
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//
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//<p><strong>提示：</strong></p>
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//
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//<ul>
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// <li><code>n == mat.length == mat[i].length</code></li>
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// <li><code>1 <= n <= 100</code></li>
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// <li><code>1 <= mat[i][j] <= 100</code></li>
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//</ul>
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//<div><div>Related Topics</div><div><li>数组</li><li>矩阵</li></div></div><br><div><li>👍 50</li><li>👎 0</li></div>
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package leetcode.editor.cn;
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// 1572:矩阵对角线元素的和
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public class MatrixDiagonalSum {
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public static void main(String[] args) {
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Solution solution = new MatrixDiagonalSum().new Solution();
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// TO TEST
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}
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//leetcode submit region begin(Prohibit modification and deletion)
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class Solution {
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public int diagonalSum(int[][] mat) {
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int sum = 0;
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int size = mat.length;
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for (int i = 0; i < size; i++) {
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sum += mat[i][i] + mat[size - 1 - i][i];
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}
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return size % 2 == 0 ? sum : sum - mat[size / 2][size / 2];
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}
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}
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//leetcode submit region end(Prohibit modification and deletion)
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}
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